The electronic industry is constantly challenged by the task of creating a system to dissipate effectively heat generated by electronic components during operation. Electronic components in use typically generate significant heat, which unless cooled, can result in damage to the components themselves as well as damage to adjacent components. Where the components are part of an intricate electronic system such as a cellular phone station or a aircraft control system, such damage can result in operating problems and/or system malfunction. In addition, such electronic systems typically must operate in relatively confined or congested areas so that the space required for air cooling systems is not available or practical. In most urban areas, for example, the space required for a fan-operated air cooling system would be prohibitively expensive and such a system would required large unsightly containers to house the fans or other air conditioning units.
One means to cool electronic components during operation in a more confined area is to use a cold plate, which essentially is an enclosed container through which fluid coolant flows to cool electronic components in contact with the cold plate. A conventional cold plate is shown in FIG. 1, and includes a plurality of bosses 4, 6 upon which the electronic components are seated, and a fluid path 2 through which a liquid coolant or air flows around the bosses 4, 6. A fluid source 7 is typically coupled to the inlet 3 of the cold plate 1 for delivering liquid coolant or air to the cold plate 1, and a receptacle 9 is typically coupled to the outlet 5 for re-cooling and/or recycling the liquid coolant or air. As further shown in this figure, the fluid path 2 associated with the conventional cold plate 1 is sequential, so that the electronic component mounted at the first boss 4 is cooled, and then the electronic component mounted at the second boss 6 is cooled, and so on. The fin area 8 surrounding each boss 4, 6 absorbs the heat generated by the electronic components to be cooled.
Where the number or configuration of electronic components to be cooled necessitates the use of more than one cold plate, the cold plates can be disposed in a vertical stack. In such a system, a single liquid coolant or air source typically delivers the fluid through a manifold to the inlet of each cold plate. To ensure that the pressure and flow rate across each cold plate is about equal, the diameter of the orifice of the inlet is adjusted for each plate. The increasing diameters of the orifices of successive cold plates force the fluid to travel up the stack and through the successive cold plates. Obtaining the proper diameter of the inlet orifices is often difficult however, and typically requires extensive testing and frequent adjustment. As a result, the time and expense required to fabricate and maintain the cooling system is increased. In the absence of such adjustment, the fluid delivered from the source will typically enter the first cold plate in greater proportion before traveling to cold plates disposed above the first plate, resulting in fluid starvation at the top-most cold plate.
It is therefore an object of the present invention to provide a cold plate and system for cooling electronic elements that provides a substantially uniform pressure drop across each cold plate without adjusting the diameter of the inlet orifice to each plate.
Another object of the present invention is to provide a system with substantially uniform flow across each cold plate regardless of the location of the cold plate in the stacked system.
A further object of the invention is to provide a cold plate cooling system that cools electronic components and achieves a substantially isothermal surface.
It is still another object of the present invention to provide a cold plate cooling system that uses a minimum amount of coolant.